[add] onClick_function

src/App.vue

@@ -28,6 +28,10 @@ const parameter = ref({
 })
 
 const result_value = ref("");
+
+function onClick(e: string) {
+  result_value.value += e;
+}
 </script>
 
 <template>
@@ -35,7 +39,12 @@ const result_value = ref("");
     <div class="display">{{ result_value || 0 }}</div>
 
     <div>
-      <button v-for="e in elements" :key="e" :style="parameter">
+      <button
+        v-for="e in elements"
+        :key="e"
+        :style="parameter"
+        @click="onClick(e)"
+      >
         {{ e }}
       </button>
     </div>